1. Field of the Invention
The present invention relates generally to a key structure having an optical visual effect, and more particularly, to a key structure having an improved light emitting efficiency.
2. The Prior Arts
Early laptop computers and desktop computers are usually equipped with keyboards which are incapable of emitting light. Recently, according to the progress made with respect to the backlight module technology, light emitting apparatuses have been provided to conventional keyboards by some of the keyboard manufacturers, for providing illumination to the keyboards or for ornament purpose.
Taiwanese patent publication No. 509955 discloses a light emitting keyboard. The light emitting keyboard is featured in that it includes a key portion and a backlight device. The key portion includes a bottom plate and at least one key disposed on the bottom plate. The key is adapted for upwardly and downwardly moving relative to the bottom plate. The backlight device is disposed beneath the key portion for providing a light source for the key portion from the underside of the key portion. The light source provides a light upwardly passing through the key portion so as to provide a light emitting effect to the keyboard. In addition to an object of providing the light emitting effect to the keyboard, Taiwanese patent application publication No. 509955 further concerns to configure the light emitting keyboard with a smaller thickness. However, when considered to be employed in electronic products requiring for a higher rank of portability and slimness, the keyboard proposed by Taiwanese patent application publication No. 509955 is not good enough.
A typical conventional slim keyboard generally includes a light guide plate, an isolation sheet, a light transmissive circuit board, an elastic member, and a light transmissive key cap sequentially disposed one on another in order. The light guide plate includes a circuit board and a plurality of first electrical contacts distributed thereon. The circuit board further includes a plurality of second electrical contacts positionally corresponding to the first electrical contacts. The isolation sheet is configured with a plurality of through holes positionally corresponding to the first electrical contacts and the second electrical contacts. A light source is provided at a lateral side of the light guide plate, and inputs a light inside the circuit board. The light is then reflected by optical structures provided at a bottom of the light guide plate and passes through the through holes for outputting, so that the key cap achieves an optical visual effect. Regarding the conventional light emitting keyboard structure, the light emitting efficiency cannot be improved while remaining the volume and thickness of the backlight module, unless more or brighter light sources are used.